1. Field of the Invention
The present invention relates to a spread illuminating apparatus of side light type, and particularly to a spread illuminating apparatus used as a lighting means for a liquid crystal display device.
2. Description of the Related Art
A spread illuminating apparatus of side light type in which a point light source, such as a white light emitting diode (LED), as a light source is disposed at a side surface of a light conductor plate is used as a lighting means for a liquid crystal display (LCD) device for use in a mobile telephone and the like.
Referring to FIG. 5, a typical spread illuminating apparatus 100 generally includes a light conductor plate 104 with such optical elements as a light diffuser sheet 105 and prism sheets 106a and 106b, and further a resin frame which firmly houses the aforementioned members (refer to, for example, to Japanese Patent Application Laid-Open No. 2003-315793. And, a light source (not shown), such as an LED, is disposed toward one end of the resin frame 102 so as to face one side surface (for example, a side surface 104a in the figure) of the light conductor plate 104.
Thickness reduction is ever required of a spread illuminating apparatus, and therefore a light conductor plate as a main constituent member must be reduced in thickness and also a resin frame to house the light conductor plate is required to have a lower profile. However, if the resin frame is formed by molding simply with a low profile, its rigidity is lowered which results in an insufficient mechanical strength of a spread illuminating apparatus.